1. Field of the Invention
The present invention relates to a sputtering target for forming a magnetic thin film and a fabrication method for the same, and more particularly to a sputtering target for forming a magnetic thin film and a fabrication method for the same for providing a magnetoplumbite thin film which is applicable to either magnetic devices such as a floppy disk, a hard disk and a magnetic tape, or a thin film inductor.
2. Description of the Prior Art
A magnetoplumbite thin film composed of a magnetic material has a structural formula of MO.6Fe.sub.2 O.sub.3 (here, M denotes Ba, Sr or Pb) and is known as a prospective high density magnetic recording material with a high coercive force resulting from a high crystalline magnetic anisotropy. Additionally, it has a chemical stability characteristic and improved corrosion resistance, and accordingly is applicable to a variety of fields for its magnetic, optical and electrical properties depending on the composition and the structure thereof.
An oxide thin film is formed using techniques such as a vacuum deposition, an electro-plating, a chemical vapor deposition, and a sputtering, among which the sputtering technique is relatively popular because it facilitates the controlling of its fine components and is appropriate to mass production.
In the sputtering technique used for to forming a thin film with a high melting point, mainly an argon gas is employed to ion-collide against a metallic or compound target and thus to emit target-composing elements by a mechanical momentum applied thereto, and finally to form a thin film on which the particles emitted therefrom are deposited. Therefore, the coated thin film depends largely upon the property of the sputtering target.
Japanese Laid-Open Patent Publication 5-315180 discloses a method for forming an oxide target without abnormal sparking, wherein a high density barium ferrite (BaO.6Fe.sub.2 O.sub.3) compact to serve as a target is prepared using a cold hydrostatic pressing method and then annealed in an atmosphere including oxygen.
Also, in Japanese Patent No. 1-144249, a Heusler's alloy thin film is stacked on a magnetoplumbite ferrite thin film to form an optical magnetic recording media by using an oxide target made by pulverizing, powder-compressing and sintering a powder made of from BaCO.sub.3, Fe.sub.2 O.sub.3 and TiO.sub.2.
However, when sputtering an oxide thin film by using an oxide target serving generally as a non-conductor, an alternating current must be used and also the deposition speed remains relatively low at about 50 .ANG./min. Besides, a raised input electric current for a higher deposition speed may result in a fragility of the target.
The above disadvantages are attributable to low thermal conductivity and high brittleness. For instance, the thermal conductivity constant of barium ferrite at a normal temperature stays at 0.04 W/cm K, that is, about one twentieth as high as that of iron which is at 0.803 W/cm.K, so that the target can easily become brittle because the heat occurring when the sputtering gas is ion-collided against the target concentrates mainly on the target surface.
To overcome the target embrittling problem and raise the deposition rate of an oxide, the present invention employs a reactive sputtering method applying argon and oxygen to a sputtering gas using a metallic target which was prepared by casting ion-barium alloy in the ratio of 12:1.
However, barium with a high oxidation property is easily oxidized and the slag drifting on the fusing liquid serves to change the composition. Also, the changed amount depends on dissolving conditions, thereby making it difficult to form an alloy with an exact composition. In particular, it is difficult to control the exact additional amount of Ti, Co, Si and Mn, each of which serves as an addition agent, wherein less than ten percent of each of the addition agents are added thereto for thereby improving the magnetic property of the thin film.